Microsoft takes another crack at its operating-system upgrade

Last October, Microsoft released Windows 8. With a radically new touch-friendly interface, an app store and other iPad-era trimmings--and no iconic Start button--it was a bold reimagining of the world's dominant PC operating system.

Maybe too bold. In the wake of its release, PC sales plunged by a record-setting 14% in the first quarter of this year, according to research firm IDC.

The fall is not all Windows 8's fault. The industry was already sagging, as consumers switched their spending to gadgets-come-lately like tablets and smartphones. Still, PC users might welcome a Windows upgrade that doesn't ask them to unlearn quite...